1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method, and more particularly to a semiconductor device manufacturing method including the step of etching a substrate surface by using a plasma.
2. Description of the Related Art
In a semiconductor process, a plasma is often used to etch a thin film on a semiconductor substrate.
A thin film which is made of a material such as platinum (Pt) whose vapor pressure is low is etched mainly by a physical etching. For example, a bias voltage is applied to a semiconductor substrate, thereby generating an electric field in a plasma. Due to the electric field, the ions contained in the plasma are attracted to the semiconductor substrate and etch the thin film. The Pt film is used as an electrode for a dielectric capacitor, for example.
A material such as Pt whose vapor pressure is low is etched mainly by the physical etching, in which case a reaction product adheres to the inner wall of a chamber without volatilizing. An adhering film, formed as a result of the adhesion of the reaction product to the inner wall of the chamber, peels off therefrom and causes the generation of particles. In particular, when the chamber is a quartz chamber, the adhering film undergoes a thermal stress due to a difference in thermal expansion coefficient between quartz and the reaction product, e.g. Pt, and easily peels off from the inner wall of the chamber.